1. Field of the Invention
The invention relates to communications systems and more particularly to systems for providing simultaneous voice, data and control systems communications.
2. Description of the Related Art
U.S. Pat. No. 4,612,634, issued Sept. 16, 1986 to John Bellamy, assigned to the same assignee as the present invention, describes a communication system that performs as an Integrated Digital Network ("IDN") capable of simultaneous voice, data and control communications throughout the system network. U.S. Pat. No. 4,612,634 is hereby incorporated by reference.
The IDN described in the above referenced patent has a flexible architecture that permits post installation changes in voice, data and control signal distribution and can be installed through telephone interconnect wiring in existing building structures.
The IDN taught in the referenced application includes a matrix switch and a plurality of user ports for exchanging voice, data and control digital signals between the matrix switch and user equipment. The digital signals comprise single samples of each signal type from each user port in each IDN sample time interval.
The IDN further comprises a transmission system for concentrating user port digital signal samples of each sample time interval, by common signal type, into multiple bit channel signals for exchange between the user ports and matrix signal ports of the matrix switch, the matrix switch interconnecting each channel signal from one or more user ports, back through the transmission system to one or more user ports.
The user ports of the IDN include station bearer and signalling channels. The transmission system includes, among other components, a plurality of station multiplex/demultiplex circuits (referred to hereinafter as "SMXs") each responsive to a cluster of user ports, for concentrating the digital signal samples from each port (which include both bearer and signalling channels) into channel signals for exchange with the matrix switch.
The IDN is a digital, Pulse Code Modulated ("PCM") information handling system for voice, and simultaneous handling of data signal communication between IDN stations serviced by IDN station multiplexers.
All bearer information carried by the IDN, i.e. voice, data and signal information, are switched through the matrix for transmission through the system. This allows for flexibility in configuring IDN information paths. Also, multiple levels of multiplexing are used to combine station port signals into higher order multiplex signals for transmission to the IDN matrix. This occurs remotely from the central matrix and is flexible, allowing for selected installation of any number of station ports where needed.
The remote multiplexing for the IDN is performed by Channel Multiplexers ("CMXs") which form an integral part of the IDN system as depicted in FIG. 1 of the incorporated patent. The figure shows CMXs being utilized as part of line and trunk interfaces (units 117 and 140 respectively), and further shows the CMXs in close physical proximity to and tightly physically coupled (via a shared backplane) to the Central Equipment Module (CEM). This tight coupling of the transmission system and CEM is problematic where user stations, telephone company trunk demarcation blocks, etc. are distributed through a facility. Wiring costs, rigid configuration, system size and servicability are all negatively affected by a tight coupling of the transmission system to the CEM. Furthermore, it would be desirable if equipment used to interface a CEM with an SMX and/or trunk card, were modular and capable of being remotely located from the CEM. This would facilitate system expansion, changing user needs, etc., at a low cost.
It would also be desirable if voice, data and control signals could be interfaced between a CEM, and SMXs and trunk cards, via modular, Line Interface Modules ("LIMs") and Trunk Interface Modules ("TIMs") which rely to a large extent on processing power resident at the CEM, and even beyond the CEM in a host computer to which a CEM can be coupled. This would keep the cost and servicing requirements of LIMs and TIMs to a minimum and further enhance system reliability because of the multiple independent modules.
Such an architecture, conceptually a three (or higher) level architecture comprising (1) user station equipment, (2) LIMs, TIMs and a CEM, with possible nesting to form additional layers, and (3) external processing resources coupled to the CEM, would provide significantly greater equipment and processing resource distribution options, lower cost LIMs and TIMs (since processing resources could be concentrated at the CEM or beyond), etc., making for a truly integrated office control system. The aforementioned SMXs could conveniently be located in either of levels one or two. This system, to which the present invention is directed, is hereinafter referred to as an Integrated Office Controller (IOC).
The IOC will be recognized by those skilled in the art to significantly depart from the IDN's two level architecture which uses the tightly coupled hardware alluded to hereinbefore, for performing the LIM, TIM and CEM functions (one level) and for exchanging signals between SMX's, user ports and user equipment via the other "level". Furthermore, no external processing resources coupled to the CEM were contemplated as part of the IDN's architecture.
Further yet, the IOC will be recognized by those skilled in the art to depart from prior art systems such as AT&T's ESS number 5, NEC's 2400 and Intecom's IBX, where equipment that performs the LIM and TIM functions require the "intelligence" to perform the switching, concentration and processing functions that are decentralized to the CEM (and possibly further away from the user side of the CEM) in the IOC architecture.